Pneumatic hoist.



No. 689,140. Patented Dec. I7, |90l. G. F. STEEDMAN.

PNEUMATIC HUIST.

(Application led Mar. 7, 1901.) (No Model.) Sheets-Shast l.

(Application ld Mar. 7, 1901.)

2 Sheets-Sheet 2.

(No Model.)

l Ho.. wAsumureN o l:

to and from the upper end of the cylinder,

"UivrTE-n STATES l .armar Ormea'.

GEORGE F. STEEDMAN, OF ST. LOUIS, MISSOURI.

PNEUMATICI-loner.

SPECEFICATON 'forming part of LettersEatentl No. 689,140, dated December 17, 1901.

Serial No. 50,243. (No model.)

To all whom t may concern:

Be it known that I, GEORGE F. STEEDMAN, a citizen of the United States, residing at the city of St. Louis, in the State of Missouri, have invented a certain new and useful Im provement in Pneumatic Hoists, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, forming `part of this specification, in which- Figure 1 is a vertical sectional View through my improved air-hoist. Fig. 2 is a top plan view of the same. Fig. 3 is a detail View, on the line 3 3 of Fig. t, of my improved form of valve, showing the same in position on the valve-casing. Fig. 4. is a sectional vview on line 4 4, Fig. 3. Fig. 5 is a top plan view of the valve-casing. Fig. 6 is a sectional view on line 6 6, Fig. 3. Fig. 7 is a sectional view on line 7 '7, Fig. 4. Fig. 8 is an inside elevational view of the valve-cap. Fig. 8@ is a side elevational view of said cap. Fig. 9 is an edge elevational view of the valve. Fig. 9a is a plan view showing the inner face of the valve. Fig. 10 is a sectional view through the hollow valve-stein, and Fig. 11 is an end view of said valve-stem.

This invention relates to a new and useful improvement in air-hoists, and more particularly to the valve mechanism for controlling the admission and exhaust of compressed air the hoists being of that type where the lower chamber in the cylinder is constantly supplied with pressure.

The object of my invention is to provide a valve which will remain tight after long use and one which will be sensitive and quick acting, means being employed in connection therewith for automatically returning the valve to its neutral or non-operative position when released by the operator.

In Figs. 1 and 2 I haveshown an air-hoist substantially the same in many respects to that shown and-described in United States Letters Patent No. 652,983, granted to me July 3, 1900. In said patent the valve controlled the admission and exhaust of pressure to and from the lower end of the cylinder, the chamber in the upper end of the cylinder constant communication with the source of air-supply, while the valve controls the admission and exhaust of pressure to and from the upper end of the cylinder. By such a control a more economical use of air is effected, because the difference in the areas of the upper and lower faces of the piston, due to the presence of the piston-rod on the lower side, enables a preponderance of pressure to move the piston in either direction, depending upon the position of the controlling-valve, whose control is conlined to the chamber at the upper end of the cylinder.

In the drawings, A indicates the cylinder, B the piston, l) the piston-rod, and O theryoke on the lower end of the piston-rod.

a indicates an eye arranged in the upper cylinder-head by which the cylinder A may be suspended in position.

D indicates a valve-casing appropriately chambered and provided with suitable ports, with which cooperates a valve E.

Referring now to Figs. 3 and Ll, 1 indicates a supply-pipe through which air is conducted to a chamber 2 in the valve block or casing, said chamber having a constantly-open port 3, leading from the valve-chamber 2 into the interior of the housing-cap'G, while a constantly-open passage A leads to the lower end of the cylinder A, whereby motive fluid is constantly supplied to the valve-chamber and to the cylinder beneath the piston. 5 indicates a pipe which establishes communication between the upper end of the cylinder A and a chamber 6 in the valve-block D. This chamber 6 is provided with a port 7, which is controlled by the valve E. Valve E is contained in a valve-chamber formed by the housing-cap G and is mounted upon a hollow valve-stem F, the outer end of the passage 8Ct in the valve-stem communicating with a recess 8 in the inner face of the valve F., while said passage also communicates with a chamber 9 in the valve block or casing D, this chamber 9 being the exhaust-chamber of the hoist and constantly open to the atmosphere. Valve E is housed by a cap-piece G,

IOO

(see Figs. 4 and 6,) between which cap and the valve is arranged a spring g for holding the valve to its seat. As indicated in Fig. 3, the supply-pipe 1 communicates with the chamber 2 of the valve-casing, and this chamber in turn communicates through the port 4 with the portion of the cylinder below the piston-head. Furthermore, said chamber 2 communicates through the port 3 with the chamber formed by the housing-cap Gr. The before-mentioned communications are constantly open. The chamber 6 in the valveblock communicates with the passage 8 in the valve-stem F, and this passage opens into the exhaust-chamber 9, said communications being constantly open; but when the parts are in the positions shown in Figs. 3 and 4 the entrance to the chamber 8 is closed by a solid portion of the wall of the valve-casing. The chamber G com municates through the pipe with the upper portion of the cylinder above the piston-head,and said chamber 6 has a port 7, which leads into the chamber formed by the housing-cap G; but when the parts are in the position shown in Figs. 3, 4, and 6 this port 7 is closed by the wing e 0f the valve. Assuming that the apparatus has never been operated and that the hoist is in raised position, as shown in Fig. 1, when air under pressure is turned into the pipe l,

\ the parts remaining as illustrated in Figs. 3,

4, and 6, said air fills the cylinder A below the piston-head B and also Hows through the port 3 into the chamber formed by the housing-cap G, the hoist being thus held in its elevated position. It is now desired to lower the hoist. The valve E is rotated to the right until the wing e uncovers the port '7. This permits the air from the pipe l to liow through the chamber 2, port 3, chamber formed by the housing-cap and port 7 into the chamber 6, and thence through the pipe 5 into the cylinder A above the piston-head B. The passage from the chamber 2 to the lower portion of the cylinder has not been closed, but owing to the fact that, as previously explained, the upper area of the piston-head is greater than its lower area a greater pressure is exerted above the piston-head than below, and consequently the piston-head B is forced downwardly, expelling the air below the pistonhead, said air iiowing backwardly through the port4into the chamber2and then mixing with the air from the source of pressure which Iiows through the port 3 into the housing-cap chamber and the chamber 6. To arrest the downward movement of the piston-head and its load, it is only necessary to close the port 7,

when the air-above said piston-head will be trapped. To cause the piston-head to continue its descent, the valve E is again turned to the right to open the port 7, as before described. Assuming that the piston-head B has been brought to a position of rest (with the valve E'as shown in Fig. 3) and that it is desired to elevate the same, the valve is turned to the left to bring the Valve-chamber 8 over the port 7. A passage is thus opened through the pipe 5, chamber 6, port 7, valve-chamber 8, and valve-stein passage 8nu between the chamber of the cylinder A above the pistonhead and the exhaust-chamber 9. The air from the source of supply acts with full pressure upon the lower surface of the pistonhead, as previously described, (the passage between the source of supply and the portion of the cylinder below the piston-head being constantly open,) and the said piston-head is raised and expels the air above the same through the exhaust-chamber 9. In rising the piston always has the full pressure available for lifting a load up to the capacity of the apparatus, depending upon the amount of pressure admitted thereto. Port 7 is provided with leads on each side, so that the edges c and e of the wing c can graduate the admission and exhaust of pressure to and from the upper end of the cylinder, and so control the speed of the descent and ascent of the piston.

I have not deemed it necessary to illustrate lin this application in detail the mechanism for manipulating the valve E, but will state that the inner end of the valve-stem F is provided with a handle II, with which coperates appropriate mechanism for restoring the valve to a lapped position, or a position in which the wing e closes the port 7. This automatic restoration of the valve forms no part of my present invention.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is

l. In an air-hoist, the combination with a cylinder, piston, and piston-rod,l of a chambered valve-block' in constant communication with the lower end of the cylinder and its valve-chamber, its port leading from the valve-chamber to. the upper end of the cylinder, said port being provided with leads 0n each side and a valve in said chamber for-cooperating with said port for admitting and exhausting pressure to and from the upper end of the cylinder,whereby, upon the admission of pressure to the upper end of the cylinder, said pressure, by reason of' the presence of the piston-rod on the lower side of the piston, will preponderate and cause said piston to descend, and a reduction of pressure in the upper end of the cylinder will enable the constant pressure beneath the piston to raise said piston; substantially as described.

2. In an air-hoist, the combination with a cylinder, piston, and piston-rod, of a valveblock formed with chambers 2, 6 and 9, an inlet-pipe leading into chamber 2, said chamber being in communication with the lower end of the cylinder, a pipe leading from chamber 6 to the upper end of the cylinder, chamber 9 being an exhaust-chamber, ports 3 and 7 for establishing communication with chambers 2 and 6 and a valve-chamber, the former of said ports being constantly open, a valve in the IOD valve-chamber formed with a recessed wing for coperating with the port 7, and a hollow valve-stem opening into the exhaust-chamber 9 for establishing communication between the port 7 and said exhaust-chamber through the recess in the wing of the valve and said hollow valve-stem; substantially as described.

3. In an air-hoist, the combination with a cylinder, piston, and piston-rod, of a valveblock formed with chambers 2, G and 9, an inlet-pipe leading into chamber 2, a pipe connecting chamber 6 with the upper end of the cylinder above the piston, a passage connecting chamber 2 with the cylinder below the piston for constantly admitting full pressure at this point, a cap-piece attached to the valveblock for forming a valve-chamber into which pressure is constantly admitted from chamber 2, a port 7 for establishing communication between the valve-chamber and the chamber 6 to admit pressure above the piston, a valve mounted in said valve-chamber and provided with a recessed wing, a spring for holding said valve to its seat, a hollow Valve-stein whose opening is in constant communication with the recess in the valve-wing at one end, and at the other end in constant communication with the exhaust-chamber 9, and a handle on said valve-stem for rotating the same and its carried valve; substantially as described.

4. In a balanced pneumatic hoist, the combination with the cylinder and its piston, of a valve-block having a chamber connected directly with the source of pressure-supply, a constantly open port 4 leading from said chamber to the lower end of the cylinder, a constantly open port 6 leading from said chamber into a valve-chamber, and avalve in said chamber for directing pressure to, or exhausting pressure from the upper end of the cylinder; substantially as described.

ln testimony whereof I hereunto afix my signature, in the presence of two Witnesses, this 5th day of March, 1901.

GEORGE F. STEEDMAN.

Vitnesses: v

GEORGE BAKEWELL, HARRY L. AMED. 

